Existing apparatus for supplying and placing electrical surface mount components typically include a frame, a board handling system for supplying circuit boards, a plurality of component feeders, and one or more placement heads. The plurality of component feeders are normally fixed to the frame and supply components to respective feeder pick-up position. The placement head or heads are movable laterally and longitudinally, i.e., in the X and Y coordinate axes, and have at least one vacuum spindle thereon which is movable vertically, i.e., in the Z coordinate axis and rotationally around the .theta. axis, to place the components onto a circuit board. The placement head shuttles between the component feeder pick-up positions where it picks-up one or more components and the designated positions above the substrate where the vacuum spindles place the picked-up components onto the substrate. However, these "pick-and-place" surface mount machines do not maximize high speed placement capabilities as the placement head must continuously shuttle between the component pick-up position and the designated placement positions above the substrate.
Prior pick-and-place surface mount machines which fall within the above described classification include machines which are manufactured and marketed by Universal Instruments Corporation of Binghamton, N.Y. under the designation "General Surface Mount Application Machines" GSM-1.
In these machines, bulk components are fed to a pick position by loose component feed devices. Escapement mechanisms such as a rotary wheel affixed to the end of loose feeders are used to separate the components for pick up by the placement head.
Additional prior art includes U.S. Pat. No. 5,044,875 to Hunt et al, disclosure of a method and apparatus for positioning electrical components 32 in which a magazine 34 of stacked electrical components is coupled to, and movable with, a vacuum tube 36. As depicted in FIG. 1, the magazine 34 receives a plurality of chips 32 arranged in a vertical stack. The weight of the stack assists the downward gravity feed of components. A sliding block 38 reciprocates along an axis 40 between a position under the stack and a position under a vacuum tube 36. Initially, the sliding block is positioned beneath and adjacent to the vertical stack of chips. The sliding block 38 is moved towards the vacuum tube 36, Such movement causes a projection 44 on the sliding block 38 to strip the lowermost chip from the bottom of the magazine, and move the chip toward the vacuum tube 36. The vacuum applied through tube 36 causes the chip to move upward against the vacuum tube 36. The sliding block 38 is moved back to its initial position below the magazine 34, and the chip is transported downward by the tube 36 until it is pressed into a circuit board at the desired site. Upon pressing the chip into the circuit board site, the vacuum is discontinued and the tube 36 is vertically raised to its initial position above chamber 42.
While this arrangement does not apparently need to shuttle a pick-and-place head between a pick station and a place station between each deposited component, it does include a number drawbacks. First, because the chips are vertically stacked, they are susceptible to the phenomenon of adhering together. This can cause the chips to hang up in the supply magazine, or to fail during the chip feed or stripping operations. Further, this arrangement is limited to feeding and placing a small number of chips in a nearly stacked magazine, and fails to provide a way to permit the feeding and depositing of a large number of components which are stored in bulk form, i.e., randomly oriented in a cartridge. Additionally, the reciprocating nature of the sliding block between only a receiving and delivery station may be disadvantageous by failing to provide suitable electronic chip component inspection and detection capabilities at intermediate stations.
Therefore, a translating placement head machine for supplying components and placing the components on a substrate at high speed with a minimum of reloading down time was needed which would eliminate the need to shuttle between a pick station and a place station, and would permit the feeding of a large number of components from a bulk source and facilitate the detection of properly supplied components. The present invention was developed to accomplish these and other objectives.